1. Field of the Invention
The present invention relates to an inverter apparatus which converts a DC input voltage into an AC voltage, and supplies the AC voltage thus converted to a load.
2. Description of the Related Art
In recent years, liquid crystal display TVs, which provide a TV having a thin shape and a large size, are becoming popular as replacements for CRT-based TVs. Liquid crystal display TVs include multiple cold cathode fluorescent lamps (which will be referred to as “CCFLs” hereafter) or external electrode fluorescent lamps (which will be referred to as “EEFLs” hereafter) arranged on the back face of a liquid crystal panel on which video images are to be displayed, which are used as light-emitting backlights.
The CCFL or EEFL is driven using an inverter (DC/AC converter) which boosts DC voltage of around 12 V, and which outputs the voltage thus boosted in the form of AC voltage, for example. The inverter converts the current flowing through the fluorescent lamp into voltage, and returns the voltage thus converted to a control circuit as a feedback voltage, thereby controlling the ON/OFF operation of a switching element based upon the voltage thus fed back. For example, related art is disclosed in the Patent documents listed later.
Here, let us consider an arrangement in which multiple fluorescent lamps are driven using the AC voltage boosted by the inverter. The light emission luminance of each fluorescent lamp is determined by the current that flows through the fluorescent lamp itself. Accordingly, in order to provide uniform light emission by multiple fluorescent lamps, or in order to produce a desired difference in the light emission luminance, there is a need to control the current that flows through each fluorescent lamp.
However, such an arrangement in which a feedback operation is performed for the current that flows through each of the multiple fluorescent lamps requires a control circuit arranged for each fluorescent lamp. However, in a case in which several to tens of fluorescent lamps are driven such that they emit light at the same time in an application such as a Liquid crystal display TV or a liquid crystal monitor, an arrangement that includes a great number of built-in control circuits is undesirable from the perspective of the mounting area, costs, and power consumption.
Here, let us consider an arrangement in which multiple fluorescent lamps are driven using the AC voltage boosted by the inverter. The light emission luminance of each fluorescent lamp is determined by the current that flows through the fluorescent lamp itself. Accordingly, in order to provide uniform light emission by multiple fluorescent lamps, or in order to produce a desired difference in the light emission luminance, there is a need to control the current that flows through each fluorescent lamp.
However, such an arrangement in which a feedback operation is performed for the current that flows through each of the multiple fluorescent lamps requires a control circuit arranged for each fluorescent lamp. However, in a case in which several to tens of fluorescent lamps are driven such that they emit light at the same time in an application such as a Liquid crystal display TV or a liquid crystal monitor, an arrangement that includes a great number of built-in control circuits is undesirable from the perspective of the mounting area, costs, and power consumption. The present applicant has proposed an inverter which is capable of solving such a problem (Patent document 5). With the inverter apparatus disclosed in Patent document 5, the currents that flow through multiple fluorescent lamps are appropriately controlled by a single feedback system (control circuit).